EP3867293A1 - Anhydrously curing polyisocyanate-based adhesives - Google Patents

Abstract

The invention relates to adhesives which are characterized in that they cure in the absence of water and at room temperature in such a way that isocyanurate groups are formed.

Description

 Polvisocvanate-based water-free curing adhesives

The present invention relates to adhesives and coatings with a high ratio of isocyanate groups to isocyanate-reactive groups and their use. These adhesives are characterized in that they cure without the presence of water and at room temperature with the formation of isocyanurate groups.

Adhesives based on polyisocyanates which cure at room temperature are known in the prior art (Leimenstoll, Stepanski, polyurethane adhesives, Springer Fachmedien, Wiesbaden, 2016; EP 1 343 832 Bl; EP 2 566 906 Al). This hardening is mediated by the formation of polyureas. This process requires water, which reacts with isocyanate groups to release carbon dioxide to form amines, which subsequently react with isocyanate groups to form fluorine groups.

For this reason, such adhesive compositions are not suitable for applications in which dry substrates are bonded to one another without moist room air having access to the adhesive joint. Furthermore, the formation of carbon dioxide during the training is disadvantageous because this creates bubbles in the adhesive joint, which weaken the stability of the connection. This problem becomes more and more serious as the adhesive joint increases in thickness, since the larger the amount of adhesive, the greater the amount of carbon dioxide. With the use of oxazolidines as chemically blocked chain extenders, the formation of carbon dioxide can be reduced, but it has to be put up with considerable odor and VOC emissions due to the volatile blocking agent released from the oxazolidine.

Two-component systems made of polyols and isocyanates are also known as adhesives (Leimenstoll, Stepanski, polyurethane adhesives, Springer Fachmedien Wiesbaden 2016; EP 1 343 832; CN 107652939; Z. Zaggias, R. Karrer, L. Thiele, Adhesion Kleben und Dichten, 40, 7 , 1996 page 26). The mechanical properties of these adhesives depend very much on the correct mixing ratio of the two components, as this directly affects the degree of crosslinking of the polymer.

Compounds which contain transition metals, in particular tin, are often used as catalysts for the abovementioned adhesives, since they can be metered particularly well and show high reactivity. However, the tendency of these transition metal compounds to remain in the bond is undesirable, since this also catalyzes the back reaction, ie the cleavage of the urethane bond, and the use of transition metal compounds may require appropriate labeling of the adhesive formulation. US 5,556,934 describes polymerizable compositions which are used for gluing bristles of a brush. The molar ratio of isocyanate groups to groups reactive with isocyanate must not be higher than 4: 1 in order to prevent foaming.

US 2002/0091222 describes polymerizable compositions for bonding rubber that cure at room temperature. The primary crosslinking mechanism is the formation of polyureas. Crosslinking of isocyanate groups with one another by the formation of isocyanurate groups is only intended to break down excess isocyanate groups. Therefore, the molar ratio of isocyanate groups to groups reactive with isocyanate is at most 2.2: 1.0.

The object of the present invention was to provide a coating composition which cures at room temperature without the addition of water or atmospheric moisture and is particularly suitable under these conditions for the production of thick adhesive joints.

In a first embodiment, the present invention relates to a coating composition comprising a) a polyisocyanate composition A with an average isocyanate functionality of at least 1.5; and

 b) At least one catalyst B, which catalyzes the reaction of NCO groups to iso cyanurate groups and / or uretdione groups at 23 ° C .; wherein the isocyanate content of the coating composition is at least 5% by weight, based on the total weight of the coating composition.

In a preferred embodiment, the coating composition according to the invention contains at least one compound C which, on average, contains at least 1.0 isocyanate group-reactive group per molecule.

In a further embodiment, the coating composition according to the invention contains fillers D.

In yet another embodiment, the coating composition according to the invention contains additives E.

A “coating composition” is a mixture of the above-mentioned components, which is suitable for coating a surface with a hardening film. The coating composition is particularly preferably used as an adhesive for the material connection of two Workpieces. The coating composition is applied to at least one of the two surfaces before the two surfaces are brought into contact with one another. The coating composition may optionally contain additional components as defined below in this application.

The coating composition according to the invention has an isocyanate group content of from 5.0 to 60.0% by weight, preferably from 7.0 to 45.0% by weight, more preferably from 10.0 to 30.0% by weight and most preferably from 12.0 to 25% by weight.

In a preferred embodiment of the present invention, the organic phase of the coating composition according to the invention has an isocyanate group content of from 5.0 to 60.0% by weight, preferably from 7.0 to 45.0% by weight, more preferably from 10, 0 to 30.0% by weight and most preferably from 12.0 to 25% by weight. “Organic phase” is understood here to mean the entirety of all components of the coating composition which are homogeneously miscible with the polyisocyanate composition A.

In a preferred embodiment of the present invention, the coating composition contains less than 0.1% by weight, preferably less than 0.05% by weight, particularly preferably less than 0.01% by weight and very particularly preferably less than 0.005% by weight % Transition metals. "Transition metal" in the sense of the present application are tin, zinc, zirconium, titanium, iron. Cobalt, nickel, scandium, ytrium, niobium, molybdenum. In a particularly preferred embodiment of the present invention, the coating composition according to the invention is free of tin , Zinc, zirconium and titanium.

The coating composition according to the invention is preferably characterized by a water content of at most 1.5% by weight, more preferably at most 0.5% by weight, even more preferably at most 0.3% by weight and very particularly preferably at most 0.1% by weight. -% marked (determined according to DIN EN ISO 15512: 2017-03, method B2).

In a preferred embodiment of the present invention, the molar ratio of isocyanate groups to isocyanate-reactive groups in the coating composition according to the invention is at least 2: 1 and more preferably at least 3: 1 and even more preferably at least 5: 1. "Groups reactive with isocyanate "For the purposes of the present patent application are hydroxyl, amino and thiol groups.

Polyisocyanate composition A

The term “polyisocyanate composition A” denotes the entirety of all compounds present in the coating composition with at least one isocyanate group. The polyisocyanate composition A preferably contains at least one compound selected from the group consisting of monomeric polyisocyanates, oligomeric polyisocyanates and isocyanate-terminated prepolymers.

The term “polyisocyanate” as used here is a collective name for compounds which contain two or more isocyanate groups in the molecule (this is understood by the person skilled in the art to mean free isocyanate groups of the general structure -N = C = 0). Simplest and most important representatives of these polyisocyanates are the diisocyanates, which have the general structure 0 = C = NRN = C = 0, where R is usually aliphatic, cycloaliphatic and / or aromatic radicals.

The totality of all molecules contained in the polyisocyanate composition A with at least one isocyanate group preferably has an average NCO functionality per molecule of 1.5 to 6.5, more preferably 1.8 to 5.0 and particularly preferably 2.0 to 4 , 5 on.

In principle, polyisocyanates with aliphatic, cycloaliphatic, araliphatic and aromatic bound isocyanate groups are equally suitable as constituents of the polyisocyanate composition A.

For reasons of availability and cost, it is particularly preferred to use polyisocyanates with aliphatically and aromatically bound isocyanate groups. Polyisocyanates or polyisocyanate mixtures based on HDI, PDI, BDI, TDI, MDI and multicore MDI homologues (PMDI) are particularly preferred.

Due to the multiple functionality (> 2 isocyanate groups), a large number of polymers (e.g. polyurethanes, polyureas and polyisocyanurates) and low molecular weight compounds (e.g. those with uretdione, isocyanurate, allophanate, biuret, iminooxa) can be made from polyisocyanates - Prepare diazinedione and / or oxadiazinetrione structure).

In this application, the term “polyisocyanates” refers to monomeric and oligomeric polyisocyanates alike. However, in order to understand many aspects of the invention, it is important to distinguish between monomeric polyisocyanates and oligomeric polyisocyanates this means polyisocyanates which are composed of at least two monomeric polyisocyanate molecules, ie compounds which represent or contain a reaction product of at least two monomeric polyisocyanate molecules. Said monomeric polyisocyanates are preferred diisocyanates, ie monomeric isocyanates with two isocyanate groups per molecule. In contrast to the isocyanate-terminated prepolymers defined further below in this application, oligomeric polyisocyanates are characterized by a molecular weight of at most 900 g / mol, preferably at most 800 g / mol and particularly preferably at most 700 g / mol. The production of oligomeric polyisocyanates from monomeric diisocyanates is also referred to here as a modification of monomeric diisocyanates. This “modification”, as used here, means the reaction of monomeric diisocyanates to oligomeric polyisocyanates with urethane, uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure.

For example, hexamethylene diisocyanate (HDI) is a "monomeric diisocyanate" because it contains two isocyanate groups and is not a reaction product from at least two polyisocyanate molecules:

HDI

In contrast, reaction products of at least two HDI molecules which still have at least two isocyanate groups are "oligomeric polyisocyanates" within the meaning of the invention. Representatives of such "oligomeric polyisocyanates" are based on the monomeric HDI, e.g. the HDI isocyanurate and the HDI biuret, which are each made up of three monomeric HDI building blocks:

HDI isocyanurate HDI biuret

(idealized structural formulas)

According to the invention, the proportion by weight of isocyanate groups, based on the total amount of isocyanate component A, is at least 5.0% by weight.

In principle, monomeric and oligomeric polyisocyanates are equally suitable for use in the isocyanate component A according to the invention. Accordingly, isocyanate component A can consist essentially of monomeric polyisocyanates or essentially oligomeric polyisocyanates. However, it can also contain oligomeric and monomeric polyisocyanates in any mixing ratio. Monomers and oligomeric polyisocyanates can be found in the polyisocyanate composition A is present in any mixing ratio with one or more isocyanate-terminated prepolymers.

In a preferred embodiment of the invention, the polyisocyanate composition A used as starting material in the trimerization is low in monomer (i.e. low in monomeric polyisocyanates) and already contains oligomeric polyisocyanates. The terms “low in monomer” and “low in monomeric polyisocyanates” are used synonymously here in relation to the polyisocyanate composition A.

A "low-monomer" polyisocyanate composition A has a proportion of monomeric diisocyanates of at most 20% by weight, preferably at most 15% by weight, more preferably at most 10% by weight, even more preferably at most 5% by weight and particularly preferably at most 2% by weight, based in each case on the weight of the isocyanate component A. In a particularly preferred embodiment of the present invention, the polyisocyanate composition A is essentially free of monomeric polyisocyanates. In this embodiment, the proportion of monomeric polyisocyanates is based on the total weight of the polyisocyanate composition A. preferably at most 1.0% by weight, particularly preferably at most 0.5% by weight and very particularly preferably below 0.1% by weight.

Polyisocyanate compositions which are low in monomer or essentially free of monomeric isocyanates can be obtained by carrying out at least one further process step in each case after the actual modification reaction to separate off the unreacted excess monomeric diisocyanates. This separation of monomers can be carried out in a particularly practical manner by processes known per se, preferably by thin-layer distillation under high vacuum or by extraction with suitable solvents which are inert to isocyanate groups, for example aliphatic or cycloaliphatic hydrocarbons such as pentane, hexane, heptane, cyclopentane or cyclohexane. Further possibilities for reducing the monomer content include reaction with compounds which contain isocyanate-reactive groups which react selectively (preferably) with isocyanate monomers, as described, for example, in EP1201695A1.

According to a further particular embodiment of the present invention, the polyiso cyanate composition A contains monomeric monoisocyanates or monomeric isocyanates with an isocyanate functionality greater than two, ie with more than two isocyanate groups per molecule. The addition of monomeric monoisocyanates or monomeric isocyanates with an isocyanate functionality greater than two has proven to be advantageous in order to influence the network density of the adhesives. Particularly practical results are obtained if the isocyanate component A has a proportion of monomeric monoisocyanates or monomeric isocyanates with an isocyanate functionality greater than two in the isocyanate component A of at least 2% by weight and at most 20% by weight, preferably at most 10% by weight and more preferably at most 5% by weight, in each case based on the weight of isocyanate component A. In this context, particularly preferred monomeric isocyanates are trisiocyanatononane and stearyl isocyanate.

According to the invention, the oligomeric polyisocyanates can have, in particular, uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure. According to one embodiment of the invention, the oligomeric polyisocyanates have at least one of the following oligomeric structure types or mixtures thereof:

 Uretdione isocyanurate allophanate biuret iminooxadiazinedione oxadiazinetrione

According to a preferred embodiment of the invention, the polyisocyanate composition A consists of at least 80% by weight of an oligomeric polyisocyanate, the isocyanurate structure fraction of which is at least 50 mol%, preferably at least 60 mol%, more preferably at least 70 mol% more preferably at least 80 mol%, even more preferably at least 90 mol% and particularly preferably at least 95 mol% based on the sum of the oligomeric structures present in said oligomeric polyisocyanate from the group consisting of uretdione, isocyanurate and allophanate , Biuret, iminooxadiazinedione and oxadiazinetrione structure.

According to a further preferred embodiment of the invention, the polyisocyanate composition A contains an oligomeric polyisocyanate which, in addition to the isocyanurate structure, contains at least one further oligomeric polyisocyanate with uretdione, biuret, allophanate, iminooxa diazinedione and oxadiazinetrione structure and mixtures thereof.

The proportions of uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazin trione structure in a polyisocyanate can be determined, for example, by NMR spectroscopy. ¹³ C-NMR spectroscopy, preferably proton-decoupled, can preferably be used here, since the oligomeric structures mentioned provide characteristic signals.

Regardless of the underlying oligomeric structure (uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure), an oligomeric polyisocyanate composition A to be used in the process according to the invention preferably has an (average) NCO functionality of 1.5 to 5 , 0, preferably from 2.3 to 4.5. Particularly practical results are obtained if the polyisocyanate composition A to be used according to the invention has an isocyanate group content of 9.0 to 60.0% by weight, preferably 12.0 to 30.0% by weight, based in each case on the weight of the Isocyanate component A has.

Manufacturing processes for the oligomeric polyisocyanates to be used according to the invention with uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure are described, for example, in J. Prakt. Chem. 336 (1994) 185-200, in DE-A 1 670 666, DE-A 1 954 093, DE-A 2 414 413, DE-A 2 452 532, DE-A 2 641 380, DE-A 3 700 209, DE-A 3 900 053 and DE-A 3 928 503 or in EP-A 0 336 205, EP A 0 339 396 and EP-A 0 798 299.

Suitable polyisocyanates for the preparation of the polyisocyanate composition A to be used in the process according to the invention and the monomeric and / or oligomeric polyisocyanates contained therein are any, in various ways, for example by phosgenation in the liquid or gas phase or by a phosgene-free route, such as e.g. by thermal urethane cleavage, accessible polyisocyanates. The monomeric polyisocyanates listed below are particularly suitable.

Said monomeric polyisocyanates as such - i.e. without prior conversion to oligomeric polyisocyanates - are also preferred components of the polyisocyanate composition A.

In the case of an isocyanate with aliphatically bonded isocyanate groups, all the isocyanate groups are bonded to an sp ³ -hybridized carbon atom. Preferred polyisocyanates with aliphatically bound isocyanate groups are n-butyl isocyanate and all isomers thereof, n-pentyl isocyanate and all isomers thereof, n-hexyl isocyanate and all isomers thereof, 1,4-butyl diisocyanate, 1,5-diisocyanatopentane (PDI), 1,6- Diisocyanatohexane (HDI), 2-methyl-l, 5-diisocyanatopentane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-trimethyl-l, 6-diisocyanatohexane 1, 10-di-isocyanatodecane, and triisocyantononane.

In the case of an isocyanate with cycloaliphatically bonded isocyanate groups, all the isocyanate groups are bonded to carbon atoms which are part of a closed ring composed of carbon atoms. This ring can be unsaturated at one or more points as long as it does not acquire an aromatic character due to the presence of double bonds. Preferred polyisocyanates with cycloaliphatically bound isocyanate groups are cyclohexyl isocyanate, 1,3- and 1,4-diisocyanatocyclohexane, 1,4-diisocyanato-3,3,5-trimethylcyclohexane, 1,3-diisocyanato-2-methylcyclohexane, 1,3-diisocyanato- 4-methylcyclohexane, l-isocyanato-3,3,5-trimethyl-5-isocyanato-methyl-cyclohexane isophorone diisocyanate; (IPDI), l-isocyanato-l-methyl-4 (3) -isocyanatomethylcyclohexane, 2,4'- and 4,4'-diisocyanatodicyclohexylmethane (H12MDI), 1,3- and 1,4-bis (isocyanatomethyl) - cyclohexane, bis (isocyanatomethyl) norbornane (NBDI), 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane, 4,4'-diisocyanato-3,3 ', 5,5'-tetramethyldicyclohexylmethane, 4,4'-diisocyanato-l, -bi (cyclohexyl), 4,4'-diisocyanato-3,3'-dimethyl-l, -bi (cyclohexyl), 4,4'-diisocyanato-2,2 ' , 5,5'-tetra-methyl-l, l'-bi (cyclohexyl), 1,8-diisocyanato-p-menthan, 1,3-diisocyanato-adamantane and 1,3-dimethyl-5,7-diisocyanatoadamantane.

In the case of an isocyanate with araliphatically bound isocyanate groups, all the isocyanate groups are bound to alkylene radicals, which in turn are bound to an aromatic ring. Preferred polyisocyanates with araliphatically bound isocyanate groups are 1,3- and 1,4-bis (isocyanatomethyl) benzene (xylene diisocyanate; XDI), 1,3- and 1,4-bis (l-isocyanato-l-methylethyl) - benzene (TMXDI) and bis (4- (l-isocyanato-l-methylethyl) phenyl) carbonate.

In the case of an isocyanate with an aromatically bonded isocyanate group, all the isocyanate groups are bonded directly to carbon atoms which are part of an aromatic ring. Preferred isocyanates with aromatically bonded isocyanate groups are 2,4- and 2,6-diisocyanatotoluene (TDI), 2,4'- and 4,4'-diisocyanatodiphenylmethane (MDI), 1,5-diisocyanatonaphthalene, tris (p-isocyanatophenyl) -thiophosphate and triphenylmethane-4,4 ', 4 "triisocyanate.

In a further embodiment, the polyisocyanate composition A contains compounds which, in addition to the isocyanate group, contain further non-isocyanate-reactive groups. For example, these are silane groups, the compounds are then isocyanatosilanes. An organosilicon group which has at least one organic radical bonded via an Si — O bond, for example an alkoxy or acyloxy group, is referred to as a silane group. Such silane groups are also known to the person skilled in the art as organoalkoxysilane or organoacyloxysilane. Silanes have the property of hydrolyzing to organ silanols on contact with moisture, that is to say forming groups with at least one silanol group (Si-OH group), and polymerizing to organosiloxanes by subsequent condensation. Silane or silanol groups can also react with polar groups on the substrate surface to form covalent bonds, which can improve the flow of adhesives to substrates. The isocyanatosilanes according to the invention are preferably isocyanatomethylsilanes or isocyanatopropylsilanes, which are best available commercially, and silane and isocyanate group-containing reaction products of flydroxy and / or amino and / or thiosilanes with polyisocyanates, not all of the isocyanate groups having been reacted, because, for example, the flydroxy and / or amino and / or thio groups are reacted with the isocyanate groups in a stoichiometric deficit. The isocyanatosilane is very particularly preferably selected from the group consisting of 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 1-isocyanatomethyltrimethoxysilane, 1-isocyanatomethyltriethoxysilane, 1-isocyanatomethylmethyldimethoxysilane and 1-isoxysiloxysilane. All silanes can also be present in the form of their oligomers containing siloxane groups. In a preferred embodiment of the present invention, the polyisocyanate composition A consists of at least 80% by weight, more preferably at least 90% by weight, even more preferably at least 95% by weight and most preferably at least 98% by weight from polyisocyanates with aliphatically bound isocyanate groups.

Isocyanate-terminated prepolymers

As part of the polyisocyanate composition A are isocyanate-terminated prepolymers with a number average molecular weight of at least 400 g / mol, preferably at least 500 g / mol, more preferably at least 600 g / mol and even more preferably at least 700 g / mol. The molecular weight of suitable prepolymers is preferably at most 22,000 g / mol, preferably at most 15,000 g / mol, more preferably at most 9,000 g / mol and particularly preferably at most 5,000 g / mol. Particularly preferred isocyanate-terminated prepolymers have a number average molecular weight between 500 g / mol and 5,000 g / mol.

In addition to the isocyanate-terminated prepolymer, the polyisocyanate composition A can also contain monomeric and / or oligomeric polyisocyanates. This is particularly preferred for those prepolymers whose isocyanate content is too low to achieve the required isocyanate contents of the polyisocyanate composition A defined above. If the isocyanate content of the prepolymer used or a mixture of at least two prepolymers is high enough, the polyisocyanate composition A can also consist exclusively of isocyanate-terminated prepolymers.

Isocyanate-terminated prepolymers are obtained by reacting monomeric or oligomeric polyisocyanates with compounds which contain an average of more than one isocyanate-reactive group per molecule, the reaction mixture having a molar excess of isocyanate groups compared to the isocyanate-reactive groups. The compounds which contain on average more than one isocyanate-reactive group per molecule are preferably polyols and / or polyamines, the reaction mixture having a molar excess of isocyanate groups compared to amino and hydroxyl groups. Appropriate manufacturing processes are well known to those skilled in the art.

Polyacrylates, polycarbonates, polyesters, polyurethanes or polyethers which are functionalized with at least two NCO-reactive groups, preferably hydroxyl groups, can preferably be used as polyols for building up the isocyanate-terminated prepolymers which can be used according to the invention. Mixtures of at least two of the aforementioned components can also be used. Polyethers are particularly preferred as polyols because they have a flexible and elastic structure that can be used to produce compositions that have excellent elastic properties. Here, polyethers are not only flexible in their basic structure, but at the same time resistant. For example, in contrast to polyesters, for example, water and bacteria do not attack or decompose polyethers. Polytetramethylene polyols, polyoxyethylene polyols and polyoxypropylene polyols, in particular polyoxyethylene diols, polyoxypropylene diols, polyoxyethylene triols and polyoxypropylene triols, are particularly suitable.

The polyols to be used according to the invention preferably have a number average molecular weight of 400 to 22,000 g / mol. In particular, the NCO-reactive polymers to be used according to the invention have a number average molecular weight of 500 to 15,000 g / mol, preferably 600 to 9,000 g / mol, particularly preferably 700 to 5,000 g / mol. These molecular weights are particularly advantageous since the corresponding prepolymers have a balanced ratio of viscosity (easy to process), strength and elasticity.

Particularly advantageous viscoelastic properties can be achieved if NCO-reactive polymers with a narrow molar mass distribution and thus a low polydispersity are used. The polydispersity represents the ratio of weight-average to number-average molecular weight Mw / Mn. The NCO-reactive polymer preferably has a polydispersity of at most 5, preferably at most 2.5, particularly preferably at most 1.5.

In a further advantageous embodiment, NCO-reactive polymers with a bimodal or multimodal molecular weight distribution are used. Bimodality is defined here as the product of a blend of more than one NCO-reactive polymer with a poly dispersity of at most 5, preferably at most 2.5, particularly preferably at most 1.5. In a particularly preferred embodiment, this mixing can also take place via the preparation of the isocyanate prepolymer using various polyols with different molecular weight distribution and composition in the preparation of the inventive isocyanate composition.

Unless otherwise stated, the number and / or weight average molecular weight is determined by gel permeation chromatography (GPC) according to the specification of DIN 55672-1: 2016-03 with THF as an eluent against a polystyrene standard.

Polyether polyols which can be prepared by the so-called double metal cyanide catalysis (DMC catalysis) are particularly preferred. This is described, for example, in US Pat. No. 5,158,922 (for example Example 30) and EP 0 654 302 (page 5, line 26 to page 6, line 32). Polyether polyols produced in this way are distinguished by a particularly low polydispersity, by a high average molecular weight and by a very low degree of unsaturation. Corresponding products are available, for example, from Covestro Deutschland AG under the name, Acclaim ^® .

The polyols to be used according to the invention preferably have an average OH functionality of 1.2 to 3, particularly preferably 1.5 to 2.1. The OH functionality of a connection is to be understood as the mean OH functionality. It indicates the average number of hydroxyl groups per molecule. The average OH functionality of a compound can be calculated based on the number average molecular weight and the hydroxyl number. Unless otherwise stated, the hydroxyl number of a compound is determined according to the standard DIN 53240-1 (2012).

Particularly suitable are polyoxyalkylene diols or polyoxyalkylene triols with a degree of unsaturation less than 0.02 mEq / g (determined according to the specification in ASTM D4671-16) and with a number average molecular weight (determined by GPC) in the range from 2,000 to 30,000 g / mol, and Polyoxyethylene diols, polyoxyethylene triols, polyoxypropylene diols and polyoxypropylene triols with an average molecular weight of 400 to 22000 g / mol. So-called ethylene oxide-terminated ("ethylene-endcapped") polyoxypropylene polyols are also particularly suitable. The latter are obtained if propylene oxide is first used as a monomer in the preparation for the polymerization and then ethylene oxide is used as a monomer instead of propylene oxide before termination of the polymerization.

Also suitable are hydroxyl group-terminated polybutadiene polyols, such as, for example, those which are prepared by polymerizing 1,3-butadiene and allyl alcohol or by oxidation of polybutadiene, and their hydrogenation products.

Also suitable are styrene-acrylonitrile grafted polyether polyols, such as are commercially available for example under the trade name Lupranol ^® by the company Elastogran GmbH, Germany.

Particularly suitable polyester polyols are polyesters which carry at least two hydroxyl groups and are prepared by known processes, in particular the polycondensation of hydroxycarboxylic acids or the polycondensation of aliphatic and / or aromatic polycarboxylic acids with dihydric or polyhydric alcohols.

Suitable polycarbonate polyols are, in particular, those which are obtainable by reacting, for example, the above-mentioned alcohols used to construct the polyester polyols with dialkyl carbonates such as dimethyl carbonate, diaryl carbonates such as diphenyl carbonate or phosgene. Polycarbonate diols, in particular amorphous polycarbonate diols, are particularly suitable. Further suitable polycarbonate polyols are those which, in addition to polycarbonate groups, also contain polyether groups contain and arise for example by polymerization of propylene and / or ethylene oxide and carbon dioxide in the presence of suitable catalysts.

Other suitable polyols are poly (meth) acrylate polyols.

Other suitable polyols are “polymer polyols”, for example polyether polyols containing polymers and / or copolymers of vinyl monomers such as, in particular, acrylonitrile, styrene, alphamethylstyrene, methyl (meth) acrylate or hydroxyethyl (meth) acrylate, and also polyureas or polyhydrazodicarbonamides ( PHD) or polyurethanes, the two phases forming a stable, storable dispersion and the polymer being partially grafted onto the polyether polyol or being covalently bound to the polyether polyol.Polymer polyols in which the solid polymer is a copolymer of acrylonitrile and styrene (SAN ) or a polyurea or polyhydrazodicarbonamide (PHD) or a polyurethane. These polymer polyols are particularly easy to prepare and store. SAN is very particularly preferred. This is particularly hydrophobic and therefore advantageous in combination with isocyanates. The polyether polyol of the polymer Polyol is preferably a polyoxyalkylene polyol, which by ring-opening polymerization of oxiranes, in particular ethylene oxide and / or 1,2-propylene oxide, with the aid of a starter molecule having two or more active hydrogen atoms, in particular water, glycols such as 1,2-ethanediol, 1,2 and 1,3-propanediol, Neopentyl glycol, diethylene glycol, triethylene glycol, polyethylene glycols, dipropylene glycol, tripropylene glycol or polypropylene glycols, or triols, in particular glycerol or 1, 1, 1 - trimethylolpropane, or sugar alcohols, in particular sorbitol (D-glucitol), or diphenols, especially bisphenols Amines, in particular ammonia, ethylenediamine or aniline, or a mixture thereof, is produced. As the polymer polyol are preferably commercially available types which are mainly used for the production of polyurethane foams, and in particular the SAN polyols Lupranol ^® 4003/1, Lupranol ^® 4006/1 / SC10, Lupranor ^® 4006/1 / SC15 , Lupranol ^® 4006/1 / SC25, Lupranol ^® 4010/1 / SC10, Lupranol ^® 4010/1 / SC15, Lupranol ^® 4010/1 / SC25, Lupranol ^® 4010/1 / SC30 or Lupranol ^® 4010/1 / SC40 (all from BASF), Desmophen ^® 5027 GT or Desmophen ^® 5029 GT (both from Covestro Deutschland AG), Voralux ^® HL106, Voralux ^® HL108, Voralux ^® HL109, Voralux ^® HL120, Voralux ^® HL400, Voralux ^® HN360, Voralux ^® HN370, Voralux ^® HN380 or Specflex ^® NC 700 (all from Dow), Carador ^® SP27-25, Caradol ^® SP30-15, Caradol ^® SP30- 45, Caradol ^® SP37-25, Caradol ^® SP42-15, Caradol ^® SP44-10 or Caradol ^® MD22-40 (all from Shell), and the PHD polyol Desmophen ^® 5028 GT (from Covestro). Of these, the SAN polyols, in particular the commercially available types mentioned, are particularly preferred.

Also suitable are polyhydroxy-functional fats and oils, for example natural fats and oils, in particular castor oil, or oleochemical polyols obtained by chemical modification of natural fats and oils, which are obtained, for example, by epoxidation of unsaturated oils and subsequent ring opening with carboxylic acids or alcohols Epoxy polyester or epoxy polyether, or polyols obtained by hydroformylation and hydrogenation of unsaturated oils.

Also suitable are polyols which are obtained from natural fats and oils by degradation processes such as alcoholysis or ozonolysis and subsequent chemical linkage, for example by transesterification or dimerization, of the degradation products or derivatives thereof obtained in this way. Suitable breakdown products of natural fats and oils are in particular fatty acids and fatty alcohols and fatty acid esters, in particular the methyl esters (FAME), which can be derivatized, for example by hydroformylation and hydrogenation, to give hydroxy fatty acid esters.

Also suitable are polycarbonate polyols, also called oligohydrocarbonols, for example polyhydroxy-functional ethylene-propylene, ethylene-butylene or ethylene-propylene-diene copolymers, as are produced, for example, by Kraton Polymers, USA, or polyhydroxy-functional copolymers from dienes, such as 1,3-butanediene or diene mixtures and vinyl monomers such as styrene, acrylonitrile or isobutylene, or polyhydroxy-functional polybutadiene polyols, for example those which are prepared by copolymerization of 1,3-butadiene and allyl alcohol and can also be hydrogenated.

Also suitable are polyhydroxy-functional acrylonitrile / butadiene copolymers, as they can be manufactured under the name Hypro ^® CTBN from the company Emerald Performance Materials, LLC, USA, for example, from epoxides or aminoalcohols and carboxyl-terminated acrylonitrile / butadiene copolymers, which are commercially available.

Commercial polyisocyanates can be used as polyisocyanates for the preparation of the prepolymer. Diisocyanates are preferably used, particularly preferably monomeric diisocyanates with a molecular weight in the range from 140 to 400 g / mol with aliphatic, cycloaliphatic, araliphatic and / or aromatically bound isocyanate groups.

Suitable monomeric diisocyanates are in particular those from a group of polyisocyanates comprising 1,4-diisocyanatobutane (BDI), 1,5-diisocyanatopentane (PDI), 1,6-hexamethylene diisocyanate (HDI), 2-methyl-l, 5-diisocyanatopentane, l, 5-diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-trimethyl-l, 6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and 1,4-diisocyanatocyclohexane, 1 , 4-diisocyanato-3,3,5-trimethylcyclohexane, 1,3-diisocyanato-2-methylcyclohexane, 1,3-diisocyanato-4-methylcyclohexane, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (Isophorone diisocyanate; I PDI), l-isocyanato-l-methyl-4 (3) -isocyanatomethylcyclohexane, 2,4'- and 4,4'-diisocyanato-dicyclohexylmethane (H12MDI), 1,3- and 1,4 -Bis (isocyanatomethyl) cyclohexane, bis- (isocyanato-methyl) -norbornane (NBDI), 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane, 4,4'-diisocyanato-3,3 ', 5.5' -tetramethyldicyclohexylmethane, 4,4'-diisocyanato-l, l'-bis (cyclohexyl), 4,4'-diisocyanato-3,3'-dimethyl-l, l'-bi (cyclohexyl), 4,4 ' -Diisocyanato-2,2 ', 5,5'-tetra-methyl-l, l'-bi (cyclohexyl), 1,8- Diisocyanato-p-menthan, 1,3-diisocyanatoadamantane, 1,3-dimethyl-5,7-diisocyanatoadamantane, 1,3- and 1,4-bis (isocyanatomethyl) benzene (xylylene diisocyanate; XDI), 1,3- and 1,4-bis (l-isocyanato-l-methylethyl) benzene (TMXDI), bis (4- (l-isocyanato-l-methylethyl) phenyl) carbonate, 2,4- and 2,6-di-isocyanatotoluene (TDI), 2,4'- and 4,4'-diisocyanatodiphenylmethane (MDI), 1,5-diisocyanatonaphthalene and mixtures thereof.

Other diisocyanates that are also suitable can also be found, for example, in Justus Liebigs Annalen der Chemie Volume 562 (1949) pp. 75-136.

In a preferred embodiment, the polyisocyanate is selected from the group consisting of 1- isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (IPDI), 1,6-hexamethylene diisocyanate (HDI), 2,4- and / or 2 , 6-tolylene diisocyanate (TDI), 2,4'- and 4,4'-diisocyanatodiphenylmethane (MDI), H12MDI and mixtures thereof.

In a further preferred embodiment, the polyisocyanate is a mixture comprising 4,4'-diisocyanatodiphenylmethane and homologous multinuclear compounds (PMDI), produced, for example, by phosgenation of reaction products of aniline and formaldehyde, the preparation of which is described, for example, under WO / 2017/125302.

In a further embodiment, the polyisocyanate composition A contains isocyanate-terminated prepolymers which, in addition to the isocyanate group, contain further nonfunctional groups which do not react with isocyanate groups. These are preferably silane groups. The prepolymers are then prepolymers containing isocyanate and silane groups. An organosilicon group which has at least one organic radical bonded via an Si — O bond, for example an alkoxy or acyloxy group, is referred to as a silane group. Such silane groups are also known to the person skilled in the art as organoalkoxysilane or organoacyloxysilane. Silanes have the property of hydrolyzing to organ silanols on contact with moisture, that is to say forming groups with at least one silanol group (Si-OH group), and polymerizing to organosiloxanes by subsequent condensation. Silane or silanol groups can also react with polar groups on the substrate surface to form covalent bonds, which can improve the adhesion of adhesives to substrates. Isocyanate-terminated prepolymers which contain silane groups in addition to the isocyanate group can be prepared in ways known to those skilled in the art. For example, they can be produced by reacting polymers which contain isocyanate groups and isocyanate-reactive groups in one molecule with isocyanatosilanes such as 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 1-isocyanato-methyltrimethoxysilane, 1-isocyanatomethylethylethylmietoxysilane, 1-isocyanatomethylethylethylmietoxysilane, 1-isocyanatomethylethylethylmietoxysilane. Another exemplary production method comprises the reaction of the above-described isocyanate-terminated prepolymers with hydroxyl, thio or aminosilanes, the hydroxyl, amino and thio groups being in a stoichiometric deficit the isocyanate groups are implemented. Aminosilanes are preferably used, particularly preferably secondary aminosilanes, such as, for example, N-butyl-N-propyltrimethoxysilane or N-cyclohexal-N-methylmethyldimethoxysilane. All silanes can also be present in the form of their siloxane group-containing oligomers.

In a further embodiment, the polyisocyanate composition A contains isocyanate-terminated prepolymers which, in addition to the isocyanate group, contain epoxy groups, and the compounds are then prepolymers containing isocyanate and epoxy groups.

Catalyst B

Any catalyst which catalyzes the crosslinking of isocyanate groups to isocyanurate groups and / or uretdione groups at 23 ° C. is suitable as catalyst B. A test procedure for determining the suitability of the catalyst involves filling 20 g of a mixture of the polyisocyanate composition A and the catalyst to be tested into a glass vessel with a volume of 25 ml, which was then covered with dry nitrogen, sealed and stored at 23 ° C. Here, polyisocyanates with aromatically bound isocyanate groups are represented by an isocyanate-polypropylene oxide polyether prepolymer, build-up component methylene diphenyl diisocyanate, NCO content approx. 15.4 percent by weight, NCO functionality approx. 2.1, viscosity approx. 1,800 mPas as a model compound. Polyisocyanates with aliphatically and / or cycloaliphatically bound isocyanate groups are as a by a polyisocyanurate, build-up component HDI, NCO content approx. 21.8 percent by weight, NCO functionality approx. 3.4, viscosity approx. 3,000, residual monomers Represents model connection.

If no curing is shown in this test, the amount of catalyst is doubled in further experiments up to a catalyst content of at most 5% by weight (based on the catalytically active fraction, without solvent).

Suitable catalysts in a concentration of at most 5% by weight lead to a hardening of the reaction mixture within 24 hours, which is defined by the fact that the mass solidifies and when the bottle is held with the opening facing downwards within 30 minutes at 23 ° C. less than 10% by weight of the contents flow out of the bottle. It is preferred here that at least 20%, more preferably at least 30%, particularly preferably at least 50% of the free isocyanate groups present in the polyisocyanate composition A react to form isocyanurate groups in the period of 24 hours after mixing with the polyisocyanate.

In the present application, a “catalyst” is also understood to mean a mixture of different compounds, provided that this mixture has the desired catalytic activity. Suitable catalysts B for the process according to the invention are in principle all compounds which accelerate the trimerization of isocyanate groups to give isocyanurate structures at temperatures of at most 50 ° C., preferably at most 40 ° C. and very preferably at most 30 ° C. and very particularly preferably at most 23 ° C. This property of a potential catalyst can be determined by performing the test described above at the temperature in question. Since the formation of isocyanurate, depending on the catalyst used, is frequently accompanied by side reactions, for example dimerization to give uretdione structures or trimerization to form iminoxadiazinediones (so-called asymmetric trimerizates), the term “trimerization” is also intended to be synonymous in the context of the present invention for these additional oligomerization reactions are in which preferably isocyanate groups react with at least one other isocyanate group.

The compounds described below are particularly suitable as candidates for the test method described above. It is expected that a relevant proportion of them will meet the criteria. These include, for example, simple tertiary amines, e.g. Triethylamine, tributylamine, N, N-dimethylaniline, N-ethylpiperidine or N, N'-dimethylpiperazine. Suitable catalysts are also the tertiary hydroxyalkylamines described in GB 2 221 465, e.g. Triethanolamine, N-methyl-diethanolamine, dimethylethanolamine, N-isopropyldiethanolamine and l- (2-hydroxyethyl) pyrrolidine, or those known from GB 2 222 161, from mixtures of tertiary bicyclic amines, e.g. DBU, existing catalyst systems with simple low molecular weight aliphatic alcohols.

A large number of different metal compounds are also suitable as candidates. Suitable are, for example, the octoates and naphthenates of manganese, iron, cobalt, nickel, copper, zinc, zirconium, cerium or lead described in DE-A 3 240 613 as catalysts or mixtures thereof with acetates of lithium, sodium, potassium, calcium or Barium, the sodium and potassium salts of linear or branched alkane carboxylic acids with up to 10 C atoms known from DE-A 3 219 608, such as, for example, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid and undecylic acid , The alkali metal or alkaline earth metal salts known from EP-A 0 100 129 of aliphatic, cycloaliphatic or aromatic mono- and polycarboxylic acids with 2 to 20 carbon atoms, such as sodium or potassium benzoate, which are known from GB-PS 1 391 066 and GB-PS 1 386 399 known alkali phenolates, such as sodium or potassium phenolate, the alkali and alkaline earth oxides, hydroxides, carbonates, alcoholates and phenolates, alkali metals known from GB 809 809 salts of enolizable compounds and metal salts of weak aliphatic or cycloaliphatic carboxylic acids, such as sodium methoxide, sodium acetate, potassium acetate, sodium acetoacetic ester, lead 2-ethylhexanoate and lead naphthenate, which are known from EP-A 0 056 158 and EP-A 0 056 159 Crown ethers or polyether alcohols complexed basic alkali metal compounds, such as complexed sodium or potassium carboxylates, the pyrrolidinone potassium salt known from EP-A 0 033 581, the mono- or polynuclear complex compound of titanium, zirconium and / or hafnium known from application EP 13196508.9, how e.g. zirconium tetra-n-butylate, zirconium tetra-2-ethylhexanoate and zirconium tetra-2-ethylhexylate, and tin compounds of the type described in European Polymer Journal, Vol. 16, 147-148 (1979), such as dibutyltin dichloride, diphenyltin dichloride, triphenylstannanol, tributyltin acetate, Tributyltin oxide, tin octoate, dibutyl (dimethoxy) stannane and tributyltin imidazolate.

Other potentially suitable compounds are the quaternary ammonium hydroxides known from DE-A 1 667 309, EP-A 0013 880 and EP-A 0 047 452, such as, for example, tetraethylammonium hydroxide, trimethylbenzylammonium hydroxide, N, N-dimethyl-N-dodecyl-N- ( 2-hydroxyethyl) ammonium hydroxide, N- (2-hydroxyethyl) -N, N-dimethylN- (2,2'-dihydroxymethylbutyl) ammonium hydroxide and 1- (2-hydroxyethyl) -l, 4-diazabicyclo- [2.2. 2] octane hydroxide (monoadduct of ethylene oxide and water with 1,4-diazabicyclo [2.2.2] octane), the cyclic ammonium salts known from WO 2017/029266, the spirocyclic ammonium salts known from WO 2015/124504, the EP- A 37 65 or EP-A 10 589 known quaternary hydroxyalkylammonium hydroxides, such as N, N, N-trimethyl-N- (2-hydroxyethyl) ammonium hydroxide, which are known from DE-A 2631733, EP-A 0 671 426, EP -A 1,599,526 and US 4,789,705 known trialkylhydroxylalkylammonium carboxylates, such as N, N, N-trimethyl-N-2-hydroxypropylammonium p-tert-butylbenzoate and N, N, N-trimethyl-N-2-hydroxyprop ylammonium-2-ethylhexanoate, the quaternary benzylammonium carboxylates known from EP-A 1 229 016, such as N-benzyl-N, N-dimethyl-N-ethylammonium pivalate, N-benzyl-N, N-dimethyl-N-ethylammonium-2 ethylhexanoate, N-benzyl-N, N, N-tributylammonium-2-ethylhexanoate, N, N-dimethyl-N-ethyl-N- (4-methoxy-benzyl) ammonium-2-ethylhexanoate or N, N, N- Tributyl-N- (4-methoxybenzyl) ammonium pivalate, the tetrasubstituted ammonium-β-hydroxycarboxylates known from WO 2005/087828, such as, for example, tetramethylammonium lactate, which are known from EP-A 0 339 396, EP-A 0 379 914 and EP-A 0 443 167 known quaternary ammonium or phosphonium fluorides, such as, for example, N-methyl-N, N, N-trialkylammonium fluorides with C8-C10-alkyl radicals, N, N, N, N-tetra-n-butylammonium fluoride, N, N, N-trimethyl-N-benzylammonium fluoride, tetramethylphosphonium fluoride, tetraethylphosphonium fluoride or tetra-n-butylphosphonium fluoride, which are known from EP-A 0 798 299, EP-A 0 896 009 and EP-A 0 962 455 known quaternary ammonium - and phosphonium polyflu orides, such as, for example, benzyltrimethylammonium hydrogen polyfluoride, the tetraalkylammonium alkylcarbonates known from EP-A 0 668 271, which can be obtained by reacting tertiary amines with dialkyl carbonates, or betaine-structured quaternary ammonioalkylcarbonates, known from WO 1999/023128, such as chaternary ammonium bicarbonates such as, for example , the quaternary ammonium salts known from EP 0 102 482 and obtainable from tertiary amines and alkylating esters of acids of phosphorus, such as reaction products of triethylamine, DABCO or N-methylmorpholine with dimethyl methanephosphonate, or the tetrasubstituted ammonium salts known from WO 2013/167404 Lactams such as trioctyl ammonium caprolactamate or dodecyl trimethyl ammonium caprolactamate. A list of other potentially suitable trimerization catalysts can be found, for example, in JH Saunders and KC Frisch, Polyurethanes Chemistry and Technology, pp. 94 ff (1962) and the literature cited therein.

The following are most likely suitable for aliphatic and cycloaliphatic isocyanates: carboxylates and alcoholates, preferably carboxylates and alcoholates with alkali metal or alkaline earth metal counterions. The catalysts are optionally added by adding additives that complex the metallic counterions, e.g. Crown ether, ether, amine, acetonate etc. activated. The alcoholates and carboxylates of the alkaline earth metals are particularly preferred, and potassium neodecanoate and potassium octoate are very particularly preferred.

Quaternary ammonium and phosphonium fluorides or difluorides are also potentially suitable.

Tetrabutylphosphonium fluoride (C16H37F2P, CAS No. 121240) and potassium acetate have been proven to be suitable.

 The following are most likely suitable for aromatic and araliphatic isocyanates: carboxylates and alcoholates, preferably carboxylates and alcoholates with alkali metal or alkaline earth metal counterions. The catalysts are optionally added by adding additives that complex the metallic counterions, e.g. Crown ether, ether, amine, acetonate etc. activated. The alcoholates and carboxylates of the alkaline earth metals are particularly preferred. Potassium acetate, potassium neodecanoate and tetrabutylphosphonium fluoride have been proven to be suitable.

Isocyanate-reactive compound C

In a preferred embodiment of the present invention, the coating composition according to the invention additionally contains a compound C which contains groups reactive with isocyanate groups. Groups reactive with isocyanate groups are hydroxyl, thiol and amino groups. The isocyanate-reactive compound C preferably contains on average at least 1.0, more preferably at least 1.5 and even more preferably at least 2.1 groups reactive with isocyanate groups per molecule. The average functionality per molecule is preferably at most 3.0. It is essential to the invention that, even in the presence of an isocyanate-reactive compound C, the isocyanate group content of the coating composition is at least 5% by weight. It is further preferred that the molar ratios of isocyanate groups to isocyanate-reactive groups defined above in this application are observed.

It is also possible to use a significantly lower index if the reaction of the isocyanate groups with one another with trimerization is so significantly higher than the reaction with the isocyanate-reactive groups that as a result most groups react with trimerization. So it may be that the compound C does not react, but possibly also functions as a plasticizer or the like.

Preferred isocyanate-reactive compounds C are low molecular weight polyols with a functionality of at least two flydroxyl groups per molecule and a molecular weight of at most 500 g / mol. Particularly preferred compounds C are ethanol, 1-propanol, 1-butanol, ethanediol, glycol, 1,2,10-decanetriol, 1,2,8-octanetriol, 1,2,3-trihydroxybenzene, glycerin, 1,1,1 Trimethylolpropane, 1,1,1- trimethylolethane, pentaerythritol and sugar alcohols 1,3 propanol, 1,2 propanol, 1,4 butanediol, 1,3 butanediol, 1,5 pentanediol, 1,6-flexanediol, 1,4 pentanediol, Diethylene glycol, triethylene glycol, neopentyl glycol, amino alcohols, polyethylene glycol (PEG) 200, PEG 300, PEG 400, PEG 600, diethanolamine and triethanolamine.

The polymeric polyols described as structural components of the isocyanate-terminated prepolymers described earlier in this application can also be used, provided that they have average functionality of isocyanate-reactive groups between 1.0 and 4.0.

To improve the flow, the coating composition may contain an isocyanate-reactive compound C with an average functionality between 1.0 and 3.0. This isocyanate-reactive compound C can be combined with at least one further isocyanate-reactive compound C, which has an average functionality of at least 1.0.

In particular, primary amines and / or amino alcohols can be suitable as the isocyanate-reactive compound C, in particular in order to obtain a structurally viscous, less draining or slipping material immediately when components C and A are mixed. Suitable primary amines are, in particular, 1,5-diamino-2-methylpentane, 2,2 (4), 4-trimethylhexamethylene diamine, 1,8-octane diamine, 1,10-decane diamine, 1,12-dodecane diamine, l-amino -3-amino-methyl-3,5,5-trimethylcyclohexane, 2- and 4-methyl-1,3-diaminocyclohexane and mixtures thereof, 1,3-bis- (aminomethyl) cyclohexane, 1,4-bis- (aminomethyl ) cyclohexane, 4,4'-methylene-bis (cyclohexylamine), bis (2-aminoethyl) ether, 3,6-dioxaoctane-l, 8-diamine, 4,7-dioxadecane-l, 10-diamine, 4,7-dioxadecane-2,9-diamine, 4,9-dioxadodecane-l, 12-diamine, 5,8-dioxadodecane-3,10-diamine, 1,3-bis- (aminomethyl) benzene or a polyetheramine such as especially Jeffamine ^® D-230, D-400 or T-403 (from Fluntsman), ethanolamine, diethanolamine, and others.

Filler D

Suitable fillers are, for example, chalk, lime powder, precipitated and / or pyrogenic silica, zeolites, bentonites, magnesium carbonate, diatomaceous earth, clay, clay, tallow, titanium oxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass powder and other ground minerals. Organic fillers can also be used, in particular carbon black, graphite, wood fiber, wood flour, sawdust, pulp, cotton, pulp, wood chips, chaff, chaff, ground walnut shells and other fiber short cuts as well as other organic or inorganic pigments. Short fibers such as glass fiber, glass filament, polyacrylonitrile, carbon fiber, kevlar fiber or polyethylene fibers can also be added. Aluminum powder is also suitable as a filler. In addition, hollow spheres with a mineral shell or a plastic shell are suitable as fillers. This may for example be hollow glass beads, which are commercially available under the trade names Glass Bubbles ^®. Hollow spheres based on plastics are commercially available, for example, under the names Expancel ^® or Dualite ^® . These are composed of inorganic or organic substances, each with a diameter of 1 mm or less, preferably 500 μm or less.

For example, a highly disperse silica with a BET surface area of 10 to 500 m ² / g is used as the filler. When used, such a silica does not substantially increase the viscosity of the composition according to the invention, but does contribute to strengthening the hardened preparation. This reinforcement improves, for example, the initial strengths, tensile shear strengths and the adhesion of the adhesives, sealants or coating materials in which the composition according to the invention is used. Uncoated silicas with a BET surface area of less than 100 m ² / g, more preferably less than 65 m ² / g, and / or coated silicas with a BET surface area of 100 to 400 m ² / g, are more preferred from 100 to 300 m ² / g, in particular from 150 to 300 m ² / g and very particularly preferably from 200 to 300 m ² / g.

Alkali-aluminosilicates are preferably used as zeolites, for example sodium-potassium-aluminosilicates of the general empirical formula aK20 * bNa20 * AI203 * 2Si0 * nH20 with 0 <a, b <1 and a + b = 1. The pore opening of the zeolite used is or the zeolites used are just big enough to hold water molecules. Accordingly, an effective pore opening of the zeolites of less than 0.4 nm is preferred. The effective pore opening is particularly preferably 0.3 nm ± 0.02 nm. The zeolite (s) is / are preferably used in the form of a powder.

In one embodiment, the filler comprises naturally occurring silicates (for example clay, clay, talc, mica, kaolin), carbonates (for example chalk, dolomite), sulfates (for example barite), quartz sand, silica (in particular precipitated pyrogenic silica), metal hydroxides (for example Aluminum hydroxide, magnesium hydroxide), metal oxides (for example zinc oxide, calcium oxide, aluminum oxide) and / or carbon black.

Chalk is preferably used as the filler. Cubic, non-cubic, amorphous and other modifications of magnesium and / or calcium carbonate can be used as chalk. The chalks used are preferably surface-treated or coated. Fatty acids, fatty acid soaps and fatty acid esters are preferably used as coating agents for this, for example lauric acid, palmitic acid or stearic acid, sodium or potassium salts of such acids or their alkyl esters. In addition, other surface-active substances such as sulfate esters of long-chain alcohols or alkylbenzenesulfonic acids or their sodium or potassium salts or coupling reagents based on silanes or titanates are also suitable. The surface treatment of the chalks is often associated with an improvement in the workability and the adhesive strength and also the weather resistance of the compositions. The coating agent for this is usually used in a proportion of 0.1 to 20% by weight, preferably 1 to 5% by weight, based on the total weight of the raw chalk.

Depending on the desired property profile, chipped or ground chalk or mixtures thereof can be used. Ground chalks can be made from natural lime, limestone or marble by mechanical grinding, for example, using dry or moist methods. Depending on the grinding process, fractions with different average particle sizes are obtained. Advantageous specific surface values (BET) are between 1.5 m ² / g and 50 m ² / g.

 The fillers used to prepare the composition usually have a certain proportion of water, which can possibly lead to undesired formation of fluorine and elimination of carbon dioxide. The filler preferably comprises water in an amount of up to 1% by weight, preferably 0.005 to 0.5% by weight, particularly preferably 0.01 to 0.3% by weight, based on the mass of the filler according to the regulation in / DIN EN ISO 15512: 2017-03, procedure B2.

Additive E

In addition to components A, B, and optionally C and D, the coating composition can optionally contain additional components (additives).

For example, compounds which increase the flow of the coating composition according to the invention on special substrates can be used as additives. These can be, for example, purely physically active compounds (for example so-called tackifiers), or compounds that are able to react with reactive groups on the substrate surface.

As an additive, for example, connections can be used which produce a uniform joint thickness, for example wires, balls, etc. made of metal or glass or ceramic.

Examples of additives which can be used are: non-reactive thermoplastic polymers, such as flomo- or copolymers of unsaturated monomers, in particular from the group comprising ethylene, propylene, butylene, isobutylene, isoprene, vinyl acetate and alkyl (meth) acrylates, in particular polyethylenes (PE), polypropylenes (PP), polyisobutylenes, ethylene vinyl acetate copolymers (EVA) and atactic poly-a- Olefins (APAO).

Examples of additives which can be used are: plasticizers, in particular phthalates, trimellitates, adipates, sebacates, azelates, citrates, benzoates, diesters of ortho-cyclohexanedicarboxylic acid, acetylated glycerol or monoglycerides, or hydrocarbon resins;

Examples of additives which can be used are: rheology modifiers, in particular thickeners or thixotropic agents, for example layered silicates such as bentonites, derivatives of castor oil, hydrogenated castor oil, polyamides, polyamide waxes, polyurethanes, urea compounds, pyrogenic silicas, cellulose ethers and hydrophobically modified polyoxyethylenes.

Examples of additives which can be used are: drying agents, such as molecular sieves, calcium oxide, highly reactive isocyanates such as p-tosyl isocyanate, monomeric diisocyanates, monooxazolidines such as Incozol ^® 2 (from Incorez), orthoformic acid esters, alkoxysilanes such as tetraethoxysilane, organoalkoxysilanes such as vinyltrimiloxanes; - Adhesion promoters, for example organoalkoxysilanes such as aminosilanes, mercaptosilanes, epoxysilanes, vinylsilanes, (meth) acrylsilanes, isocyanatosilanes, carbamatosilanes, alkylsilanes, S- (alkylcarbonyl) mercaptosilanes and aldiminosilanes, and also oligomeric forms of these silanes.

Examples of additives which can be used are: stabilizers against oxidation, heat, light and UV radiation.

Examples of additives which can be used are: flame-retardant substances, in particular the fillers already mentioned aluminum hydroxide and magnesium hydroxide, and in particular organic phosphoric acid esters such as, in particular, triethyl phosphate, tricresyl phosphate, triphenyl phosphate, diphenylcresyl phosphate, isodecyldiphenyl phosphate, tris (1,3-dichloro-2-propyl (phosphate, tris (2-chloroethyl (phosphate, tris (2-ethylhexyl (phosphate, tris (chloroisopropyl) phosphate, tris (chloropropyl) phosphate, isopropylated triphenyl phosphate, mono-, bis- and tris (isopropylphenyl) phosphates of different degrees of isopropylation, resorcinol bis (diphenyl phosphate), bisphenol A bis (diphenyl phosphate) or ammonium polyphosphates, melamine and melamine derivatives such as phosphates or isocyanurates, expanding graphites, zinc borates or antimony trioxide.

Examples of additives which can be used are: surface-active substances, in particular wetting agents, leveling agents, deaerating agents or defoamers. Examples of additives which can be used are: biocides such as algicides, fungicides or substances which inhibit fungal growth.

Preferred additives are rheology modifiers, adhesion promoters, drying agents or stabilizers against UV light and / or oxidation.

In a particularly preferred embodiment of the present invention, the coating composition according to the invention also contains at least one

Urethanization catalyst. This is particularly preferred if the composition contains compounds C.

benefits

A large number of catalysts which contain no transition metals are available for the coating composition according to the invention. This is advantageous for environmental and occupational safety reasons.

Unlike adhesives that harden through the formation of urea groups, the coating composition according to the invention does not require moisture to harden. This means in particular that adhesive joints can cure in the absence of air, since no access to air humidity is required. The reaction of water with isocyanate groups also produces carbon dioxide. This can lead to the formation of air bubbles in the adhesive joint and is unfavorable for the mechanical properties, since the air bubbles are weak points. This can be acceptable for thin layers of adhesive that lead to thin adhesive joints, since little carbon dioxide is formed here. With thicker adhesive joints, however, more carbon dioxide is produced, which leads to larger bubbles and thus to more pronounced weak points.

In contrast to the known two-component polyurethane systems, the coating compositions according to the invention are comparatively insensitive to mixing errors. A slightly different mixing ratio of catalyst and polyisocyanate composition may lead to slightly faster or slower curing. However, it has only a minor influence on the final strength of the adhesive joint.

The coating compositions according to the invention are also particularly well suited for the connection of components which are coated with cathode dip lacquers. Previously, the bonding of such components required a trade-off between two disadvantages: two-component polyurethane adhesives adhere very well to the components. However, they intrinsically have a comparatively low tensile shear strength and / or generally only have a short pot life. Adhesive failure is linked to the intrinsic strength of the adhesive (cohesion) and to the adhesive strength (adhesion). If cohesion and adhesion are greater than the substrate strength, the substrate is destroyed during the adhesive test. This is generally the preferred mode of failure of an adhesive.

The study on which this invention is based has shown that the coating compositions according to the invention have very good adhesion to the cathode dip coating and at the same time have high intrinsic strength. In many cases, the corresponding adhesive joints fail because the cathode dip coating tears off the substrate, i.e. Adhesion and intrinsic tensile shear strength of the coating composition according to the invention are no longer the properties that limit the strength of the adhesive joint.

use

In the study on which the present patent application is based, it was surprisingly found that the coating compositions described above cure without the action of atmospheric moisture and at room temperature and show very good strengths even at temperatures well above room temperature. Therefore, in a further embodiment, the present invention relates to the use of the adhesive composition according to the invention defined above in this patent application for producing an adhesive joint.

The adhesive joint can be produced in any way known to the person skilled in the art. The coating composition is preferably applied to at least one of the two substrates to be connected before the two substrates are contacted with the surfaces to be connected. If necessary, this can be done under pressure. Subsequently, until the coating composition has hardened, the substrates are incubated at at least 10 ° C., preferably at least 15 ° C., more preferably at least 20 ° C. and most preferably at least 23 ° C., without moving them against one another. The upper limit of the temperature during curing is given by the decomposition temperature of the coating composition or of the workpieces to be bonded. It is preferably 250 ° C.

Since the catalysts that can be used according to the invention preferably already enable curing at 23 ° C., curing within the scope of the use according to the invention is preferably carried out at temperatures between 10 ° C. and 60 ° C., more preferably between 15 ° C. and 50 ° C., particularly preferably between 15 ° C and 40 ° C. A cured coating composition contains at most 20%, preferably at most 10%, of the free isocyanate groups originally contained in polyisocyanate composition A. This condition is preferably reached after curing at temperatures between 10 ° C and 60 ° C for 24 hours. After curing at temperatures between 10.degree. C. and 40.degree. C. for 24 hours, a state is particularly preferably reached in which at most 20% of the free isocyanate groups originally contained in the polyisocyanate composition A remain. The content of isocyanate groups can be determined by IR spectroscopy as described elsewhere in this application.

Since the curing of the coating composition according to the invention does not depend on the formation of urea groups, no moisture is required. Therefore, a coating composition having a water content of at most 1.5% by weight is preferably used. The hardening can also take place in the absence of air, since neither an entry of air humidity nor the escape of carbon dioxide is necessary. The water content is calculated by adding the free water contained in the coating composition and the water bound to the substrate. In principle, the latter is also accessible for the reaction to urea groups, albeit with a delay, since the binding to the substrate is reversible.

Substrates which are impermeable or partially impermeable to air and moisture are particularly preferably bonded. These are preferably metal, plastic and dry wood, more preferably metal and plastic. "Dry wood" is wood with a residual moisture determined according to EN 13183-1 (Darr method) of at most 10% by weight, more preferably at most 5% by weight. The substrates can be precoated, for example with lacquers It is preferred that the coating composition is applied to a surface which has an extent of at least 5 mm in both dimensions.

In a preferred embodiment of the present invention, the adhesive joint has an average thickness of at least 0.001 mm, preferably 0.05 mm, particularly preferably 0.1 mm and very particularly preferably at least 1 mm.

In principle, the method according to the invention is suitable for bonding all surfaces. Surfaces made of glass, ceramic, glass ceramic, concrete, mortar, brick, brick, plaster, natural stone, metal, plastic, leather, paper, wood, resin-bound wood materials, textiles, resin-textile composites and polymer composites are preferred.

Metals are preferably copper, iron, steel, non-ferrous metals and alloys which contain the aforementioned metals. The metal can be surface-coated, in particular by chrome plating or galvanizing. Preferred plastics are polyvinyl chloride, polycarbonate, acrylonitrile-butadiene-styrene copolymer, polymethyl methacrylate, polyethylene, polypropylene, ethylene-propylene copolymers, polyamide, polyester, epoxy resins, polyoxmethylene, ethylene-propylene-diene rubber and styrene-acrylonitrile copoly- merisat.

Since the coating composition according to the invention also cures in the absence of moisture, it is particularly well suited for the bonding of surfaces which are made of metal, plastic or dry wood, particularly preferably made of plastic or metal. The use for bonding metal surfaces which are precoated with cathode dip lacquer is furthermore preferably suitable. It is very particularly preferred here that both surfaces consist of metal, in particular metal coated with cathode dip lacquer, or plastic.

The study on which the present study is based has shown that the coating compositions according to the invention are particularly well suited for bonding metal parts which have been precoated with a cathode dip lacquer. For this reason, in a particularly preferred embodiment of the present invention, at least one of the substrates to be connected by the adhesive joint consists of metal which is coated with a cathode dip coating at the point where the coating composition is applied.

A cathode dip varnish is an immersion primer which is separated electrophoretically from an aqueous phase. Binders used for this purpose comprise compounds containing blocked isocyanate groups, which undergo crosslinking reactions under the conditions in the stoving oven in automotive OEM painting with the release of a blocking agent, described in Meier-Westhues, Polyurethane coatings, adhesives and sealants, Vincenz Network, 2007, Hanover, page 144 -145.

method

In yet another embodiment, the present invention relates to a method for producing an adhesive joint comprising the steps a) applying the coating composition according to the invention to a surface;

 b) contacting the coated surface with another surface; and c) curing the coating composition at a temperature of at least 10 ° C and at most 60 ° C.

All of the definitions given above for the coating composition and its use also apply to this embodiment. The coating composition can be applied by all methods known to the person skilled in the art and suitable for compositions of the viscosity in question.

The term “contacting” denotes a process in which the surface coated with the coating composition is physically brought together with the further surface, so that no air gap remains between the two surfaces.

It is possible according to the invention to coat the further surface with a coating composition according to the invention before both surfaces are contacted.

In the cured coating composition, at least 5%, preferably at least 20%, more preferably at least 35% and very particularly preferably at least 50% of the isocyanate groups present in the coating composition at the beginning of process step b) have been converted to isocyanurate groups. At the same time, the proportion of the isocyanate groups converted to urea groups is at most 30%, preferably at most 20% and very particularly preferably at most 10% of the isocyanate groups present in the coating composition at the beginning of process step b).

In one embodiment of the present invention, it is furthermore possible for the curing step c) to be carried out at a variable, preferably increasing, temperature. Process step c) is preferably carried out at a temperature of at most 40 ° C. until a tensile shear strength of at least 0.5 N / mm ² , preferably at least 2 N / mm ² and very particularly preferably at least 4 N / mm ^{2 is} achieved is. The process step is then continued at a temperature of at least 40 ° C. until a higher strength of preferably at least 2 N / mm ² , preferably at least 4 N / mm ² , particularly preferably at least 6 N / mm ² and very particularly preferably at least 8 N / mm ^{2 is} reached. More preferably, the curing continues at at least 50 ° C. In order to avoid decomposition of the adhesive, curing takes place at a maximum of 300 ° C. The tensile shear strength is preferably determined in accordance with DIN EN 1465, adhesives, determination of the tensile shear strength of overlap bonds.

Since the polyisocyanate component A in the presence of catalysts B in the coating compositions according to the invention cures within a few hours and thereby becomes solid or experiences an increase in viscosity which would make contacting the substrate surfaces more difficult, the coating compositions according to the invention should be prepared sufficiently shortly before application.

The period of time in which an adhesive composition provided by mixing its components can still be processed is referred to as the "pot life". The end of processing Workability is preferably defined by doubling the viscosity of the coating composition, or more preferably by thread tearing when a stir bar is withdrawn from the coating composition. The production of an adhesive joint with a coating composition that has exceeded its pot life can lead to faults such as, for example, a slower or incomplete build-up of the adhesion to the substrate.

In a preferred embodiment of the present invention, the process according to the invention contains a further process step, in the course of which the components of the coating composition according to the invention are mixed as described below. This process step takes place before process step a). It is preferred that the period between the provision of the coating composition according to the invention by mixing its components and the end of process step b) is not greater than the pot life of the coating composition used. It is particularly preferred that the period between the provision of the coating composition according to the invention and the end of process step b) is at least 5 minutes, preferably at least 10 minutes and particularly preferably at least 30 minutes.

Components A, B, C and E of the coating compositions according to the invention suitably have such a consistency that they can be mixed well with one another and with the fillers D using simple processes. Liquid and paste-like components A, B, C and E are particularly suitable for this purpose, the viscosity of the liquid or paste-like components being comparatively low at room temperature. Dosing and mixing can thus be carried out easily by hand or with commercially available dosing systems and dynamic or static mixers. Alternatively, dispersing devices can be used if e.g. solid fillers must be incorporated.

In a preferred process, all of the components A to E used in the coating compositions according to the invention are premixed in such a way that components XI and X2 are present separately from one another and these can be mixed immediately before application. XI contains the polyisocyanate components A and X2 the catalyst according to the invention. Additives and fillers can be present in component XI and / or X2.

Substances reactive with isocyanate groups are preferably a component of component X2. It may be useful to dry certain components chemically or physically before mixing them into the respective component, preferably to a low water content of at most 1.5 percent by weight. XI and X2 are therefore manufactured separately from one another. The constituents of the respective component XI and / or X2 are preferably mixed with one another with the exclusion of moisture, so that a macroscopically homogeneous mass is formed. Each component is preferably stored in a separate moisture-tight container. A suitable container is in particular a barrel, a container, a flobbock, a bucket, a canister, a can, a bag, a hose bag, a cartridge or a tube. The components XI and X2 are preferably stable in storage, that is to say that they can be stored in the respective container for several months to a year and longer before their use without their properties changing to an extent relevant to their use.

To use the composition, the two components are mixed with one another shortly before or during the application. In parts by weight, the mixing ratio between the XI and X2 is, for example, in the range from about 1: 5 to 200: 1, in particular 1: 1 to 20: 1.

XI and X2 are typically mixed using a static mixer or with the help of dynamic mixers. Mixing can take place continuously or in batches. When mixing, make sure that the two components XI and X2 are mixed as homogeneously as possible. If the mixing is inadequate, local deviations from the advantageous mixing ratio occur, which can result in a deterioration in the mechanical properties.

In a still further embodiment, X2 is first applied to at least one of the substrates to be bonded, while XI is subsequently applied to the substrate pretreated in this way or at any time to the other substrate which has not been pretreated. Alternatively, the procedure can be reversed. The components of the coating composition according to the invention are then only contacted or mixed in the joining process. This method has the advantage that, for example, pre-coated substrates can be glued with a 1-component adhesive.

The result of the method according to the invention is an adhesive joint which integrally connects the two surfaces and consists of the hardened coating composition.

In a further embodiment, the present invention relates to an adhesive joint which can be obtained by the process described above.

The following exemplary embodiments only serve to illustrate the invention. They are not intended to limit the scope of the claims in any way. Examples

Unless otherwise stated, all percentages relate to the weight.

The methods listed below for determining the corresponding parameters are used to carry out or evaluate the examples and are also the methods for determining the parameters relevant according to the invention in general.

The NCO contents are determined titrimetrically according to DIN EN ISO 11909.

Unless otherwise stated, the water content was determined in accordance with DIN EN ISO 15512: 2017-03, method B2.

The residual monomer contents of isocyanates are measured gas-graphically according to DIN EN ISO 10283 with an internal standard.

The pot life of the systems was determined as follows: The required quantities of the individual components are weighed in a PE beaker on a balance. The total weight of the mixture should be at least 50 g. Immediately after the last component has been weighed in, a stopwatch is started and the mixture is stirred intensively for about 1 minute with a stirring rod. The stirring rod is pulled out of the mixture every 30 minutes and the flow behavior of the mixture is observed. The pot life has been reached and can be read from the stopwatch when the thread breaks and the mixture no longer flows off the stir bar.

All viscosity measurements are carried out with a Physica MCR 51 rheometer from Anton Paar Germany GmbFI (DE) according to DIN EN ISO 3219 / A3. Unless otherwise stated, the stated viscosity is determined at 23 ° C.

In order to be able to observe the blooming behavior of catalyzed adhesives and sealants over time, the development of the breaking force against time is observed. For this purpose, test specimens are produced which consist of two overlapping glued substrate parts. After specified times, these are then stretched to break in a tearing machine and the required forces are measured (tensile shear strength test).

The substrates for the preparation of the test specimens were obtained from Rochholl and prior to use at least 1 week at 23 ° C / 50% rel. Humidity stored

Five test specimens consisting of 2 overlapping glued substrate parts are required for each measurement. A part of the substrate is coated in the longitudinal direction to 20 mm with the adhesive to be tested. The second substrate part is placed in such a way that the width overlap completely. The length overlap is 10 mm. After pressing them together with your hands, material coming out of the sides is removed with a spatula. 10 test specimens each are stacked in a press in such a way that the overlapping surfaces lie one above the other. The test specimens are pressed at a pressure of 0.7 N / mm2 for a specified time at 23 ° C / 50% rel. Humidity stored and removed immediately before the test. The specified times (pressing times) can be found in the following tables (in h).

The tensile shear strength was measured in each case on a tensile testing machine universal testing machine Zwick 1475 analogous to DIN EN 1465 at a feed rate of 50 mm / min. The test specimens were stretched to break and the maximum force value was determined. The results given correspond to the arithmetic mean of 5 experiments.

Process according to the invention for producing the adhesive compositions

The amounts of the starting polyisocyanates given in the following tables were weighed into a polypropylene beaker together with the amounts of the catalyst component given in the following tables and, if appropriate, the amounts of the other additives (plasticizers, fillers, “compounds C”) and with the aid a speed mixer DAC 150 FVZ (Hauschild, DE) homogenized at 2750 rpm for 1 min.

 The method according to the invention is used both for producing adhesive compositions according to the invention and not according to the invention.

The calculated NCO content of the mixture given in the following tables is calculated from the mass fraction of the various starting polyisocyanates and their NCO contents, and the mass fractions of the other components

Process according to the invention for the selection of the catalyst To select the catalysts according to the invention, about 20 g of the model substance for the starting polyisocyanate A, together with 0.6 g (based on the active component) of the catalyst component, are weighed into a polypropylene beaker and using a DAC 150 FVZ speed mixer (from Hauschild , DE) homogenized for 1 min at 2750 rpm. 20 g of the mixture are poured into a glass bottle (volume 25 ml, opening diameter 1.7 cm) under dry nitrogen and stored tightly closed at 23 ° C. for 168 hours. The state of the mixture is then assessed. For this purpose, the bottle is opened and held with the opening down for 10 min over a beaker with a known weight, so that all material that has flowed through the opening is collected. Possibly. outflown material is transferred into the beaker with a card sheet. It is determined whether more or less than 10% of the amount of material has flowed out of the bottle.

If the material is obviously liquid (viscosity at 23 ° C at most 5 Pas), the pouring test can be dispensed with, since it is assumed that more than 10% of the material will flow out.

Here, polyisocyanates with aromatically bonded isocyanate groups are available from Covestro Germany through Desmodur ^® E 23, (isocyanate-polyether prepolymer, build-up component MDI, NCO content approx. 15.4 percent by weight, NCO functionality approx. 2.1, viscosity approx. 1,800 mPas) AG represented as a model connection. Polyisocyanates with aliphatically bound isocyanate groups are represented by Desmodur N ^® 3300 (polyisocyanurate, HDI structural component, NCO content approx. 21.8 percent by weight, NCO functionality approx. 3.4, viscosity approx. 3,000) available from Covestro Deutschland AG as a model compound. If these products are not accessible, the specialist can use analog replacement products with a comparable composition. With the same diisocyanate as the build-up component, it is important to ensure that the NCO functionality and NCO content are as similar as possible. The production methods are known to the person skilled in the art or are described in the literature.

An isocyanate prepolymer with an NCO content of 27% based on a polypropylene polyether with nominal OH functionality 2, hydroxyl number 112 mg KOH / g and isophorone diisocyanate is suitable as a model compound for compounds with cycloaliphatically bound isocyanate groups. This model substance can be produced by reacting 226 g Desmophen 1110 BD (Covestro, linear polypropylene polyether polyol, hydroxyl number 112 mg KOH / g, acidity at most 0.1 mg KOH / g, viscosity at 25 ^° C approx. 140 mPas, water content 0.05%) and 744 g of Desmodur I (Covestro, isophorone diisocyanate (IPDI), purity (GC) at least> 95% of hydrolyzable chlorine not more than 160 mg / kg, NCO_Gehalt ca. 37.5%) at 100 ^Q C.

The remaining part of the mixture is poured onto a polyethylene film and this is covered with another polyethylene film. After 168 hours, the upper polyethylene film is removed and the state of the mixture is visually inspected. In the case of fully or partially cured Samples (ie if a mechanically resilient film has formed) are analyzed by IR spectrometry. For this purpose, an IR spectrometer from Perkin-Elmer (Perkin Elmer Spectrum Two) with an ATR unit is used (UATR two). Hardened samples were measured with optimal contact pressure (adjustable via the device). Liquids are measured directly on the ATR unit.

Using comparative measurements of the liquid mixtures before storage, it is examined whether the NCO groups have reduced and whether additional uretdione, isocyanurate or iminooxadiazinedione groups have formed. The position of characteristic bands can be found in the literature by the person skilled in the art or, if this is not possible, by measuring comparison spectra of model substances, which are accessible by methods known in the literature.

Output connections

Filler Omyacarb 5 GU, calcium carbonate, Omya, Germany plasticizer Jayflex DINP, diisononyl phthalate, Exxon Mobile 1,2-ethanediol, Aldrich

All of the polyisocyanates used are either commercially available from Covestro Deutschland AG or can be prepared based on readily available monomers and catalysts using the processes described in the patent literature.

Polyether A according to the invention, used as a structural component for producing isocyanate prepolymers according to the invention

The polyether PI, a difunctional polypropylene glycol polyether started on propylene glycol and having a hydroxyl number of 500 mg KOH / g, viscosity 55 mPas, water content 0.01%, prepared with potassium hydroxide as a catalyst, then worked up with sulfuric acid, distilled and filtered, was used .

Polyether B according to the invention, used as component C

Desmophen ^® 2061 BD, linear polypropylene ether polyol with the hydroxyl number 56 mg KOH / g available from Covestro Deutschland AG.

Starting isocyanate A, Desmodur ^® N3300

HDI polyisocyanate containing isocyanurate groups available from Covestro Deutschland AG. NCO content: 21.8%

NCO functionality: 3.4

Monomeric HDI: 0.1%

Viscosity (23 ° C): 3,000 mPas

Starting isocyanate B

Desmodur ^® E XP 2599, available from Covestro Deutschland AG, polyether allophanate based on 1,6-hexamethylene diisocyanate

NCO content: 6.0%

NCO functionality: 4

Monomeric HDI: 0.1%

Viscosity (23 ° C): 2,500 mPas

Starting isocyanate C

Polyether allophanate prepolymer based on 1,6-hexamethylene diisocyanate

Was prepared analogously to example la from EP 1775313, except that in this case 221.2 g of polyether PI were used. Before the zinc (II) bis (2-ethylhexanoate) was added, an NCO content of 42.9% by weight and before removing the excess 1,6-hexane diisocyanate, an NCO content of 39.9% was achieved.

NCO content: 17.0%

 NCO functionality: 4

 Monomeric HDI: 0.1%

 Viscosity (23 ° C): 2,550 mPas

Starting isocyanate D

Polyether urethane prepolymer based on 1,6-hexamethylene diisocyanate

Was prepared analogously to Example la from EP 1775313, except that in this case 221.2 g of polyether PI and 900 g of 1,6-hexane diisocyanate were used and neither isophthalic acid dichloride nor zinc (II) bis (2-ethylhexanoate) were added. The excess 1,6-hexamethylene diisocyanate was removed immediately after an NCO content of 31.4% had been reached. NCO content: 12.5%

NCO functionality: 2 Monomeric HDI: 0.1%

Viscosity (23 ° C): 4,200 mPas

Starting isocyanate E

Desmodur ^® E23

 Aromatic polyisocyanate prepolymer based on diphenylmethane diisocyanate (MDI) containing polyether groups, available from Covestro Deutschland AG

NCO content: 15.4%

 NCO functionality: 2.1

 Viscosity (23 ° C): 1,800 mPas

Starting isocyanate F

Desmodur ^® E 15

 Aromatic polyisocyanate prepolymer based on tolylene diisocyanate containing polyether groups available from Covestro Deutschland AG

NCO content: 4.4%

 NCO functionality: 2

 Monomeric TDI: 0.2%

 Viscosity (23 ° C): 7,000 mPas

Starting isocyanate G

Desmodur ^® L75 (75% in ethyl acetate), 13.3% NCO

Aromatic polyisocyanate based on tolylene diisocyanate, approx. 75% by weight in ethyl acetate available from Covestro Deutschland AG

NCO content: 13.3%

NCO functionality: 2.7

Monomeric TDI: 0.2%

Viscosity (23 ° C): 1,600 mPas Starting isocyanate H

922 g of starting isocyanate A were placed in a flat ground vessel under dry nitrogen and heated to 60.degree. 78 g of polyether 1 were then added over the course of one hour with stirring. The reaction mixture was then heated to 60 ° C. and stirred until an NCO content of 17.0% was reached.

NCO content: 17.0%

 Viscosity (23 ° C): 1,600 mPas

Catalyst Kl - tetrabutylphosphonium fluoride * nHF,

(70% by weight dissolved in isopropanol, prepared according to Example Ia from EP 0 962 454 B1, fluoride content (ion-selective electrode) 2.5%)

 Active component 70% by weight

Catalyst K2 - potassium acetate (60% by weight in diethylene glycol)

Potassium acetate and diethylene glycol are available from Aldrich.

Active component 60% by weight

Catalyst K3 potassium neodecanoate, 60% by weight

31.7 g of potassium neodecanoate, 60% by weight in di-propylene glycol methyl ether (available under the name Baerostab K 10 from Baerlocher Italia) are mixed with 44.4 g of methoxypropyl acetate, 23.9 g of crown ether 18-Crown-6.

Active component 19.0% by weight

Catalyst K4 - dibutyltin dilaurate, 95%, available from Aldrich

Active component 95%

Catalyst K5 - 2,2'-dimorpholinodieethyl ether (DMDEE), 97%, available from Aldrich

Active component 97%

Comparative tests are marked with an * below. Examples for the selection of suitable catalysts

Catalyst selection for systems with predominantly aromatic, araliphatic isocyanate groups

In accordance with the instructions given above, tests for catalyst selection were carried out using starting polyisocyanate E and various catalysts. The material obtained was examined by infrared spectroscopy (ATR-IR spectroscopy) as described above. The IR spectra were printed out as measured on A4 paper. Use a pencil to draw a horizontal line (O-line) at 100% transmission, parallel to the x-axis (wave numbers). For characteristic bands, a line perpendicular to this (signal line) is drawn up to the x-axis (wave numbers) at the wave number at which the transmission is minimal. Now the distance of the intersection of this line with the curve of the transmission values and the 0-line is determined by measuring with a ruler and given in mm.

Low transmission values result in larger distance values in mm and higher distance values in mm indicate a higher proportion of these groups in the examined sample. Alternatively, the person skilled in the art can also carry out an analog evaluation directly by comparing the transmission values of characteristic bands.

The position of characteristic bands can be found in the literature by the person skilled in the art or - if this is not possible - by measuring comparison spectra of model substances, which are accessible by methods known in the literature.

The catalysts K 1, K 2 and K 3 are sufficiently active in the model system for systems with predominantly aromatically bound isocyanate groups, since hardening can be observed (after 168 hours solid, no liquid runs out). It also shows that the content of NCO groups decreases and the content of dimers (uretdione groups) and trimers (isocyanurate groups) increases compared to the product without addition of catalyst, which is due to the lower ratio the signal intensity between NCO and trimer can be read. Apparently, Kl, K2 and K3 acted as trimerization catalysts.

Catalyst selection for systems with aliphatically bound isocyanate groups

In accordance with the instructions given above, tests for catalyst selection were carried out using starting polyisocyanate A and various catalysts. The material obtained was examined by infrared spectroscopy (ATR-IR spectroscopy).

Percentages above relate to the proportion by weight of spilled material.

The model compound without catalyst can be stored for weeks without a measurable change in the NCO content and viscosity, so only the starting value was given. The catalyst Kl is particularly active in the model system for systems with predominantly aliphatically bound isocyanate groups, since hardening can be observed (after 168 solid, no liquid runs out). The catalyst K2 is also sufficiently active and leads to curing. It also shows that the content of NCO groups decreases and the content of trimers (isocyanurate groups) increases compared to the storage-stable storage-stable model compound without addition of catalyst, which can be seen from the lower ratio of the signal intensity between NCO and trimer. Apparently, Kl and K2 acted as trimerization catalysts, with the decrease in the NCO groups using Kl being significantly faster than with K2.

Examples 1-3

It can be seen in experiment 1 * that a mixture of the starting polyisocyanates G and F with highly reactive aromatically bound isocyanate groups (NCO content 11%) without the addition of a catalyst and without access to sufficient amounts of moisture does not lead to any tensile shear strength of the bonded substrates even after 24 hours , since apparently there is no sufficient curing. In contrast to this, in experiments 2 and 3, adding catalysts K2 and Kl according to the invention without the ingress of moisture and in the absence of further compounds with isocyanate-reactive groups leads to high tensile shear strength in the event of substrate failure (detachment of the KTL coating from the sheet metal).

Examples 4-11

 1) Substrate failure

 n.b. = not determined

It can be seen that the two-component polyurethane system with DBTL as the urethanization catalyst (comparative experiment 5 *) has an unfavorable ratio of strength and pot life achieved compared to the systems according to the invention based on aliphatic and aromatic polyisocyanates. Comparative experiment 5 * has a lower strength with a shorter pot life than experiment 4 according to the invention. High tensile strengths are achieved on many typical substrates. The adhesive bonds on KTL show that after just a few hours, the strength is so high that the substrates can be handled safely. Short pressing times can be achieved in this way.

Example 12-16

In experiment 12 *, a non-inventive starting polyisocyanate with an NCO content of approx. 4% is used in combination with the catalyst K3. This adhesive composition does not lead to sufficient tensile shear strength, since after 24 hours there is apparently insufficient curing. Examples 13 to 16 according to the invention show that, with decreasing NCO content, lower tensile shear strengths are determined.

Examples 17-22

Analogously, further examples 17-22 with the catalyst C1 show that high tensile shear strengths can be achieved even when fillers and / or plasticizers are added, and these can therefore be used. However, as the NCO content of the mixture decreases, lower tensile shear strengths are also obtained here.

Claims

Claims

1. Use of a coating composition comprising a) a polyisocyanate composition A with an average isocyanate functionality of at least 1.5; and

 b) at least one catalyst B, which catalyzes the reaction of NCO groups to isocyanurate groups and / or uretdione groups at 23 ° C .; wherein the isocyanate content of the coating composition is 5% by weight to 60% by weight and the molar ratio of isocyanate groups to any isocyanate-reactive groups present in the coating composition is at least 5: 1, for producing an adhesive joint or a coating.

2. The use according to claim 1, wherein the coating composition additionally contains at least one compound C which on average contains at least 1.0 isocyanate group-reactive group per molecule.

3. The use according to claim 2, wherein the at least one compound C is selected from the group consisting of ethanol, 1-propanol, 1-butanol, ethanediol, glycol, 1,2,10-decanetriol, 1,2,8-octanetriol , 1,2,3-trihydroxybenzene, glycerin, 1,1,1-trimethylolpropane, 1,1,1-trimethylolethane, pentaerythritol, sugar alcohols, polyethylene glycol (PEG) 200, PEG 300, PEG 400, PEG 600, diethanolamine and triethanolamine

4. The use of claim 1, wherein the polyisocyanate composition A contains isocyanate-terminated prepolymers.

5. The use according to any one of claims 1 to 4, wherein the

Coating composition contains at least 5 wt .-% isocyanate groups based on the organic phase of the coating composition.

6. The use according to any one of claims 1 to 5, wherein the

Coating composition contains less than 0.1 wt .-% transition metals based on the total weight of the coating composition.

7. The use according to any one of claims 1 to 6, wherein the

Coating composition additionally contains at least one filler D.

8. The use according to any one of claims 1 to 7, wherein the polyisocyanate component A consists of at least 80 wt .-% of polyisocyanates with aliphatically bound isocyanate groups.

9. The use according to any one of claims 1 to 8, wherein surfaces selected from the group consisting of glass, ceramic, glass ceramic, concrete, mortar, brick, brick, plaster, natural stone, metal, metal coated with cathode paint, plastic, leather, paper , Wood, resin-bonded wood-based materials, textiles, resin-textile composite materials and polymer composite materials.

10. The use according to any one of claims 1 to 9, wherein the adhesive joint has a thickness of at least 1 mm.

11. The use according to any one of claims 1 to 10, wherein the curing takes place at a temperature between 10 ° C and 60 ° C and is completed after a maximum of 24 hours.

12. A method for producing an adhesive joint comprising the steps a) applying the coating composition as defined in claim 1 on a surface;

 b) contacting the coated surface with another surface; and c) curing the coating composition at a temperature of at least 10 ° C and at most 60 ° C.

13. The method according to claim 12, additionally comprising a step upstream of step a) of providing the coating composition by mixing its components, characterized in that a period of at least 30 minutes passes between the provision of the coating composition and the end of step b).

14. The method according to claim 12 or 13, wherein in step c) a temperature between 10 ° C and 40 ° C is first maintained until the adhesive joint reaches a tensile shear strength according to DIN EN 1465 for adhesives of at least 0.5 N / mm ² and then a temperature of at least 50 ° C is maintained until the adhesive joint reaches a strength of at least 2 N / mm ² .

15. The method according to any one of claims 1 to 14, wherein in step b) at least 20% of that at the beginning of step b) in the coating composition existing isocyanate groups are converted to isocyanurate groups and at most 30% of the isocyanate groups present in the coating composition at the beginning of process step b) are converted to urea groups.